1. Field
The present disclosure generally relates to fasteners, and deals more particularly with a method and apparatus for fabricating high strength composite fasteners.
2. Background
Plastic fasteners such as threaded bolts and screws have been developed for use in several applications because of their light weight, compared to metal fasteners. Plastic fasteners may be fabricated using injection molding, extrusion or compression molding techniques. It is known that plastic fasteners may be strengthened by incorporating reinforcement fibers in a plastic resin, however these reinforced plastic fasteners may nevertheless be weaker than metallic fasteners due to their relatively low fiber volume in relation to the plastic resin. In one approach, long, continuous axially aligned reinforcing fibers infused with a polymer resin are formed by a molding process. Although providing additional strength in the axial direction of the fastener, the fastener may be substantially anisotropic, rendering it unsuitable for some applications. Additionally, known reinforced plastic fasteners are difficult to fabricate, especially in high volume because of the need to layup and align continuous fibers in a mold.
Accordingly, there is a need for a method and apparatus for producing fiber reinforced, plastic fasteners that have a high fiber volume and exhibit quasi-isotropic properties. There is also a need for a method and apparatus of the type mentioned above which permits fabrication of high-strength plastic fasteners quickly and in high-volume Further, there is a need for threaded fasteners which incorporate fibers in the threads to increase thread strength.